The DTE Notebook for the Urban Organic Vegetable, Herb, and Flower Gardener.
Fertilizing
Article and photos by Rob Danforth
Myke potting mix and chicken manure
All gardens need fertilizing: this includes in-ground plots, raised beds, box beds, cold frames, and large and small containers. Plants feed on the water-soluble nutrients dissolved in the water they drink, and Mycorrhizal fungus helps the roots to accomplish this. Bags of soil will have “myco-active” or some other phrase to tell the buyer that the fungus is present. Plots and raised beds already have the fungus – another reason to practice no-till gardening.
Plants can exhaust the water-soluble nutrients in both garden soil and potting mixes and the nutrients must be replenished if future plants are to thrive. Also, because the nutrients are water soluble, rain and gardener watering can wash away nutrients and reduce the plant food.
You will note that the water that runs out the bottom of a pot is coloured light brown or pale greenish yellow because it contains water soluble nutrients (aka “plant food”) – the soil in the pot acts like a tea bag or coffee in a filter. Tip: save this “soil tea,” dilute it, and water with it next time (within 7 days) to put back the nutrients washed out.
Garden plant rotation can help save some of the available nutrients in all soils that are used year after year, since different plants consume different nutrients, at different depths and at different times of the year.
Fertilizing every year is a must, regardless. I fertilize with home grown screened compost two times a year, fall (emptying composters for winter additions), and mid-summer. Top dressing lets nature have its way with the distributed compost but you can add to your labour and mix it in if you prefer. In the fall, I cut and drop the soft parts of finished plants onto the surface of the soil to act as a winter mulch in all plots and large containers. Life in the soil will feed on it, and spent plants release some of the nutrients they have consumed – as they would in a composter or on a forest floor.
The best all-around fertilizer you can use is compost (slow release & non-burning). All plants need Nitrogen [N], Phosphorus [P], and Potassium [K] (NPK) as well as a great many trace elements (e.g., calcium, manganese, sulfur, zinc to name a few). Compost will add nutrients from A to Z, balance the pH, fight diseases over time, improve soil structure, retain moisture, and feed worms and other life in the soil. Tip: if you compost at home, you control the contents, recycle kitchen and garden waste into plant food, and save money. It is easy to do, and when done properly, composting will not annoy neighbors (see Composting, DTE Fall 2017).
Note: there are balcony composters; however, many stores and pop-up nurseries will sell compost as well as composted manure if home composting is not desirable or possible.
Well composted manure is also good, but remember that all manures can contain pathogens so handle them carefully, don’t breathe the dust, wash hands and tools, and wash produce that comes in contact with it. I would not let children helping in applying manure – my personal caution. Note: pathogens are the reason we do not put any animal products in our home composters – besides, decomposing animal products attract rats and other vermin. Chicken manure, and composted sheep, cow, and horse manure (in descending order of nutrient value – although the last three are so close in composition that it doesn’t really matter which you use) all work well but chicken manure granules have higher NPK, so use small amounts and bury them to avoid a fungus farm.
Organic chemical fertilizers are excellent, high in soluble nutrients, but not the ideal choice because they are concentrations of specific nutrients without the additional trace elements and without the extra abilities of compost to improve your garden soil. Use them according to directions, but compensate for the limitations.
Low NPK Numbers (e.g., 0.5-0.4-0.2): Some gardeners think that the higher the NPK numbers (e.g., 10-10-10 or 20-20-20) the better. However, consider the difference between fast release and slow release – like some of the pain killers we take. Compost and composted manure are slow release. Fast release high numbers fertilizers can be used on lawns (4 times a year is the industry recommendation) where there are thousands and thousands of hungry plants standing ankle to ankle that can consume 10-10-10 water-soluble plant nutrients before the rain, or you, wash it away. Food and flower gardens have, at best, tens of pampered plants (food, water, protection, and limited competition for nutrients are provided by you) and high NPK numbers can be wasted and washed away into the Ottawa river (contributing to algae blooms, oxygen depletion, and aquatic dead zones – look up the giant “dead zone” at the mouth of the Mississippi river, USA). Besides, high NPK numbers can be too strong for seedlings, and some plants may suffer burns.
Sample of some NPK numbers on products I have used:
Chemical Fertilizer: 10 – 52 – 10
Composted Manure: 1 – 1 – 1
Fish meal: 10 – 4 – 0.6
Kelp Meal: 1 – 0.15 – 1.5
Myke Potting mix: 0.5 – 0.4 – 0.2
Caution: We have good and bad years in weather. The same can be true for soils and fertilizers. I used a particular organic garden soil for many years but one year, newly purchased soil performed so badly that seeds and plants failed (e.g., weak to no seed germination, very slow growth, no fruit, frequent blossom drop, and unhappy looking plants). Time and effort tending them was wasted, not to mention the fact that good container spaces were all tied up with plant failures. I have also worked with compost given to community gardeners which would not even grow weeds!
Your best and least expensive fertilizer option is home grown compost. It is easy to do year-round composting in a back yard or even on a balcony. We green bin all fish & animal bits – both raw and cooked. Chopped up kitchen and garden fruit, vegetable, herb, weed (seedless), and flower waste as well as clean, shredded cardboard all go into our 3 composters year-round.
Please see the Down To Earth newsletter, Fall 2017, on Do-it-yourself outdoor composting for details on “HOW TO.”
Tip: the cylindrical structure of hardware cloth gives you much more control over the screening process with a shopping bin or wheelbarrow. However, a wood frame with hardware cloth to sift the compost also would work well if you lean it or mount it on legs and collect the sifted compost on a tarp – which you can drag to the delivery site.
Remember that we are what we eat, and the same is true for plants and animals (e.g., flamingoes are white birds – shrimp and other aquatic creatures that they eat changes them pink). With home grown compost as your fertilizer, you know what’s in it!
A happy garden makes a gardener happy!